Figure 1: Almost 3" of rain fell between late April and the first week of May

Nice to be done with the rain and the storms for a while, isn’t it?  Today marks the second day in a row where rain will not make an appearance, and the first such stretch since late last April (Fig. 1).  Nearly 2/3′s of a month’s worth of rain came down over a 10 day period.

Figure 2: Mississippi River forecast for La Crosse (National Weather Service)

 The recent stretch of soggy and stormy weather has had a wide array of impacts on the Coulee Region.  Severe storms knocked down trees and power lines from Alma to Blair, and caused flash flooding in Wabasha on May 2nd.  Stormy weather the morning of May 6th interfered with the La Crosse Fitness Festival’s marathon and half-marathon races.  The Black and the Trempealeau Rivers rose to near flooding early this week before receding, and the Mississippi is expected to jump up to 9 feet for a while as it absorbs all of the recent rain water (Fig 2).

Figure 3: Moderate drought has moved back to west of Rochester (U.S. Drought Monitor)

We definitely needed that hefty soaking, despite all of the unwanted side-effects of damaging storms.  I have been curious to see if the recent showers would a dent in the drought across Minnesota, and, according to the U.S. Drought Monitor’s report released today, there has been some improvement in the drought in the News 19 viewing area (Figure 3).  Abnormally dry conditions still linger in Trempealeau, Buffalo, Winona, and La Crosse counties, but drought conditions moved back west of Rochester.  Crops will still be slow to grow under these dry conditions, but any other agricultural, ground water, or fire risk issues have been lessened by the soggy stretch of weather. 

Figure 4: Since last summer, the Midwest has been below average on precipitation, especially in Minnesota, which has led to a moderate drought (Midwest Regional Climate Center)

This good news comes with a big BUT: there is still some way to go before we can be free of the drought that plagues most of Minnesota.  We are still in a precipitation deficit, so more long periods of rain are needed (Figure 4).  The U.S. Drought Monitor does paint a rosier picture going forward into this summer.  Improvement in drought conditions have been forecasted for Minnesota, with areas of southern Minnesota seeing enough precipitation ease or completely get rid of the abnormally dry conditions (Figure 5).

Figure 5: Some improvement is expected going into this summer for Minnesota's drought

My hope here is that there is a nice balance between the rain and the dry weather from here on out so we don’t get stuck with too much rain after being too dry (as in “be careful what you wish for..”).

Have any questions, comments, or just want to chat about how much you liked to disliked the recent soggy weather?  Shoot me an email at akirchner@wxow.com!

-News 19 Meteorologist Alex Kirchner.

3 ingredients are needed for dangerous fire conditions: dry air, dry brush, and gusty winds

We’ll start with the fire danger: both Minnesota and Wisconsin are at a Very High to Extreme fire danger rating.  Both mean that fires can start and spread very quickly, and are very difficult to contain, control, and stop once they get going.  We get conditions like these when the vegetation is dry, providing plenty of fuel for fires (this is especially true in southern Minnesota, where the moderate to severe drought has spread into the Coulee Region).  Dry air (humidity below 30%) is needed, as moist air will hinder the fire’s development.  The final ingredient, and a very important one for Very High to Extreme fire danger, is a strong, gusty breeze or wind.  Stronger winds will help the fire spread quickly, as it can scatter burning fuel (vegetation), embers, and sparks to rapidly spread the current fire and start new ones in other locations.  On days like these, check the DNR’s website about the day’s fire risks and restrictions and be very careful when using anything involving an open flame or sparks outside, including lighting or discarding cigarettes, working with power tools or engines, and, of course, no burning!

On the opposite side of things, icy weather invades the Coulee Region again tonight.  Temperatures will drop into the upper 20′s, which is considered a “hard freeze”.  This means prolonged exposure to subfreezing temperatures and a hard frost development, which is very damaging to unprotected crops and other cold-sensitive plants (think frostbite, but for plants- they’re cells will freeze and burst, killing parts or all of the plant).  We typically have lows like these around this time of year.  The best way to combat the killing frost is, if possible, to move plants indoors, or cover them with a blanket or heavy sheet to prevent the frost from forming on the plants.  This is tricky, though, when temperatures stay at or below freezing for an extended period, like tonight.  We usually do not see relief from the frosty nights under late this month.

Good new on both the fire and ice fronts is the weather this weekend:  Much needed rain will soak the Coulee Region between Friday and Sunday, with as much as 1 1/2 inches falling between the three days.  There is still some uncertainty this early in the week about the exact amount exactly where, but at least some precipitation is coming.  At the same time, the overnight lows will be much warmer, possibly as warm as the 50′s overnight, getting rid of the frosty nights.

As always, if you have any questions, be sure to drop me a line!  Stay warm (or cool, depending on the time of day)!- Meteorologist Alex Kirchner, akirchner@wxow.com

The fact that this month beat out the former top March by nearly 4° is impressive, considering how much warmth is needed to increase an average temperature by four degrees:

Highest Mean Temperatures for March

1) March 2012: 50.4°

2) March 1878: 47.1°

3) March 1910: 45.7°

4) March 1946: 44.5°

5) March 1945: 43.0°

One observation about March 1910: I noticed that most of the daily temperature records broken this month (9 in total!  Nearly 1/3 of the month had record-breaking days) were set in 1910.

In addition to the 9 days that set new high temperature records, there were 9 nights that had record warmth in the 60′s for the overnight temperature, and a few days with record high dew points in the 60′s.  We normally do not have dew points in the 60′s until the humid “dog days of summer”!  I know I at least will not be forgetting that beautiful stretch of 9 days in the 70′s and 80′s when it felt like summer- that was also a March record, beating out, you guessed it, March 1910.

The 9 days in a row with temperatures at 70° or higher set a record for the month of March

One final note: you might have noticed a connection here between March 2012 and March 1910.  That connection- climate variability.  Just like this past warm winter, every so often atmospheric conditions line up just right to have a record-breaking warm start to the spring season.  And it doesn’t have to happen every 100 years or so.  March 2000 and 2010 rank in the top 10 for warm March’s as well.  So enjoy the early green grass and beautiful spring weather, because at this time next year, who knows what we will be experiencing!

-Meteorologist Alex Kirchner

akirchner@wxow.com

The reason for “feeling” colder lies in the role of that constant breeze or a stiff wind.   Moisture in your skin will evaporate when exposed to a breeze.  The evaporation process creates a cooling effect, which is why a fan or a breeze feels refreshing on a hot summer day.  That same breeze does not feel nice at all during the winter because of the same effect.

We may be "feeling" a wind chill of -10° to -25° over the next few days.

Here’s a chart showing how large of an impact just a light breeze has on how frigid temperatures feel.  Wednesday night through Friday will be especially nasty, as winds stay steady between 15 and 20 mph.  Advisories will be in effect for this time period because frostbite can set in within 10 minutes with wind chill that cold.  Here’s a link on our website about frostbite for tips on how to ward off the dangerous condition, especially for parents with little kids.

Try to stay warm!  Relief arrives this weekend with temperatures in the 30′s.  -News 19 Meteorologist Alex Kirchner

Up until January 12th, I’m sure plenty of snowmobiles, sleds, and skis were collecting dust instead of powder.

Figure 1: 4.3″ of snow fell last month, which was 7″ below average, and at least 20″ behind the previous 4 Decembers.

December had an average high temperature of 35° and a whopping 4.3″ (Fig. 1) of snow for the entire month.  This month has had two record-setting 53° days, an average high of 41° until Tuesday, and just a trace of snow through Jan. 11th.

Why has this winter been so mild and relatively snow-free, despite predictions in November saying the opposite?

Let’s start with La Niña, which is influencing our weather right now. La Niña may sound familiar, as last winter was a La Niña winter. We were definitely wetter than average, especially last December.

During a La Niña event, cooler than average waters occur in the Pacific near South America (Fig. 2).  The jet stream that drives our weather gets its strength from the temperature contrast between the Equator and the North Pole, and when that contrast is weakened by a cooler Pacific, the jet sinks south.  In turn, weather patterns in North America are affected by the altered path of the polar jet (Fig. 3).

Figure 3: Usual impacts of La Niña on U.S. winters

We’ve been anything but cooler and wetter than average, so far.  Here’s the next step:  another disturbance called the Madden-Julien Oscillation (MJO) has come into play this winter (see how complex weather can be!).  I won’t bore you with the details, but the MJO can modify the jet stream further, and push it north into Canada.

Figure 4: The MJO alters the jet stream, and keeps precipitation and cold air north of the Midwest.

This matches the pattern we where in for the start of this winter (Fig. 4), with the polar jet keeping cold Arctic air bottled up in Canada (keeping us warmer than average), and keeping the main storm track north of the Midwest (less chances for snow).

Looking ahead, now that there is a decent amount of snow pack after Thursday’s storm, temperatures will stay colder than where we’ve been lately for a while (snow reflects sunlight, so the sun cannot heat up the air as easily and temperatures stay colder).

Figure 5: The CPC's forecast for the next 3 months

The Climate Prediction Center is predicting temperatures to stay near or slightly above average for the rest of winter, which may be MJO’s doing.  La Niña will still be playing a role this winter.  The CPC also has above average chances for precipitation for the Midwest (Fig. 5).  I guess that means we may have a chance at a true winter full of snow after all!  Stay tuned!

News 19 Meteorologist Alex Kirchner

Weather Academy is an education program that teaches area school children about weather processes.  They also learn the always important safety procedures during hazardous weather events.  250 students attended the afternoon assembly, accompanied by their grandparents and staff.  (Grandparents’ Day)  The assembly was followed by an in-school open house, where the kids drew Weather Windows for the Daybreak show, saw neat experiments, and practiced their forecast presentation skills in front of the Junior Weather Wall.  Overall, it was a very positive experience for the children, grandparents, staff and the forecast team!

Including Kickapoo Elementary, we will travel to six schools this school year for Weather Academy.  The schedule is as follows:

• Kickapoo Elementary – 9/22/2011
• Summit Environmental School (Summit Elementary, La Crosse) – 10/13/2011
• St. Patrick’s Catholic School (Onalaska) – 12/1/2011
• Blair-Taylor Elementary – 1/26/2012
• Sand Lake Elementary – 4/5/2012
• Seneca Elementary (Eastman, WI) – 5/3/2012

We look forward to the rest of the school year and the opportunity to help area children learn more about how the atmosphere works!

If you would like Weather Academy to come to your school, contact the forecast team at news19.weather@wxow.com.

Until next time, see you on the air!

News 19 Meteorologist Nick Grunseth

When it comes to forecasting precipitation, knowing the “percent chance” of an upcoming event is important to many people.  However, some people who put faith in this number mistakenly interpret the true definition of “percent chance” in weather terms.  If I go out on the street and ask people what it means if there’s a 30% chance of rain today, a majority will probably say it means 30% of the area will receive rain, while the other 70% will stay dry.  Some may also state ”looking at this date over the past 100 years, it rained 30 of those days.”  While it’s a good try, both of these understandings are false.

The percent chance of precipitation is also known as the probability of precipitation. (POP)  The National Weather Service has been using POPs for decades, assigning them to daily forecasts.  Basically, when a meteorologist says “there’s a 30% chance of rain today,” it means there’s a 30% chance any random point in a given area will experience measurable precipitation.   And the number isn’t just pulled out of the air.  (Pun intended, of course!)  The number 30 is determined by forecasters and computer models.   It means three out of ten times when conditions were similar in the past, it rained.  So yes, the higher the percentage, the more likely it’s going to rain or snow, but it all depends on the size and history of your forecast area.

So why the confusion?  A large part of the problem is the lack of explanation by broadcasters and internet resources.  You’ll rarely hear from a broadcaster what percent chance means; or, worse yet, the broadcast does not correctly understand the whole concept.  On internet forecast pages with percent chance listed, there’s usually no written statement next to the forecast, explaining it’s probability rather than coverage area.  The lack of explanation, combined with human nature’s urge to jump to conclusions, can lead to a misunderstanding of what the meteorologist or broadcaster is trying to relay.

The WXOW News 19 forecast team frequently displays the precipitation risk, but not the exact chance of precipitation.  You’ll hear mentions of “slight, moderate, and likely.”  You will also hear and see the terms “isolated, scattered, hit and miss, widespread,” etc.

I have many friends and colleagues that live by percent chance.  That’s perfectly fine and I don’t shun them.  Their forecasts have a lot of good, quality information too.  A POP is there to provide the meteorologist an understanding of what the atmospheric setup is like.  In my personal opinion, the reason that specific number does not make it to air is because I feel avoiding an exact percent chance as much as possible provides you, the viewer, a better idea what the weather will be like.  Remember the whole area thing?  News 19′s viewing area is far different compared to other media outlets.  It’s also not fair to write on a graphic “50%,” when that chance exists closer to Prairie du Chien compared to the “10%” that would exist in La Crosse.  Second, it can be very confusing!  I am a big fan of taking the complexity of numbers and equations and making a forecast that’s easy to understand.  More or less, you’re just trying to find out if it will rain or not, right?  So why make your experience of understanding the weather forecast similar to writing a college mid-term?  No thanks!

Thanks for reading, and feel free to post with comments or questions!

News 19 Meteorologist Nick Grunseth

We have seen our share of tornado pics, video and scenes of natural disasters this year right here in the United States, but a weekend occurrence has caught my eye and attention. A volcano in Chile erupted over the weekend. Photographers have caught an unbelievable array of stunning images of the Puyehue volcano. Here’s a sample:

For more pictures and the story details use this link.

You’ll be amazed at the images!

Dan Breeden

News 19 Chief Meteorologist

The ‘Enhanced Fujita scale’, or EF scale, is the system used to rate the strength of a tornado.  Professor Tetsuya Fujita, partnering with Allen Pearson, came up with the scale in 1971.  The scale uses the amount of damage caused by the tornado as an indicator of its strength, rather than its size.  A tornado could be over a mile wide, but if its winds are relatively weak, or it goes through a dirt field and does not hit anything, it really was not a strong tornado, was it?   Compare that to a smaller tornado fifty yards wide, but with strong winds that can demolish houses.

The ‘Enhanced’ portion of the EF scale was implemented in 2007 after a team of meteorologists and wind engineers updated the strength indicators of the scale.  Here’s a chart with the older Fujita scale, and the Enhanced Fajita scale:

Courtesy: Storm Prediction Center, National Weather Service

The National Weather Service sends out damage survey teams after a possible tornado goes through, and based on amount of damage (for example, when looking at a house roof, are there a few shingles blow off, or is part or all of the roof missing?), the survey team can derive how strong the winds were (based off of wind experiments engineers and meteorologists conduct), and from there, can derive a tornado’s strength.  If the winds were estimated to be around 100 mph, the tornado would be considered an EF-1.  Here’s a chart with the older Fujita scale, but a good description of the damage done by each type of tornado:

Courtesy: www.tornadoproject.com

Thankfully, the tornadoes that went through the Coulee Region were on the lower end of the scale, and no one was seriously injured or killed.  Any tornado is dangerous, so always be prepared or alert when severe weather threatens. 

Feel free to pass on any questions or concerns.  I would love to help!

News 19 Meteorologist Alex Kirchner